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2002 Vol. 28, No. 5

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Convergent Infinite Computation and Applications
LI Wei, MA Shi-long, SUI Yue-fei, XU Ke
2002, 28(5): 481-489.
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Classical computations can not capture the essence of infinite computations very well. This paper will focus on a class of infinite computations called convergent infinite computations and establish a logical framework for describing and analyzing how an infinite computation interacts and evolves in changing environments and what the limit of the evolution might be. A logic for convergent infinite computations was proposed by extending first order theories using Cauchy sequences,which has stronger expression power than the first order logic. A computation model,called procedure scheme,for convergent infinite computations was proposed,on the basis of classical Turing machine and formal theory sequences and their limits. It has stronger computing power than Turing machines and real machines in the sense of limit computations. As an example of application of the above study,the limit behavior of data mining was discussed by means of limits of theory sequences.
Current Status and Development Direction of Aircraft Power Technology in the World
LIU Da-xiang, CHENG Rong-hui
2002, 28(5): 490-496.
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The development course of jet engine is described. The engine which thrust weight ratio is about 8 is the power of the main fighters on active service in the developed countries. The 4th generation fighters stalling the jet engine with thrust weight ratio 10 will be gradually equipped with the army after 2003~2007, and will become the main fighting aircraft of USA and some western countries and even several neighbor countries and area of China after 2010. This paper sums up the development and key technologies of civil turbo\|fan engine and power of helicopter. The aero\|engine development will be confronted with new opportunities in the 21st century. The development direction of the main key technologies on the aircraft power in the 21st century is indicated.
Failure Analysis Diagnosis of Mechanical Equipment
ZHONG Qun-peng, ZHANG Zheng, TIAN Yong-jiang
2002, 28(5): 497-502.
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The present and development in recent decade in both practical and academic aspects of failure analysis diagnosis, prediction and prevention for mechanical and electrical equipment in China was described and summarized briefly. The category, criterion and method of pattern diagnosis were discussed. The content and method of reason diagnosis were dissertated. The category and content of mechanism diagnosis were presented. Through these deep analyses, the basic framework and concepts of the theoretic, technical, and methodological subsystems on failure analysis diagnosis were established. Therefore, the diagnosis of failure will be more accurate and scientific in the future.
Newly Developed Human, Machine and Environment Engineering Technology Science
WANG Jun, YU Jian-zu, ZHUANG Da-min, LIN Gui-ping
2002, 28(5): 503-511.
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Based on the human, machine and environment engineering system, filght vehicle environmental control and life insurance system, environment simulation technology, air conditioning, recent research of science of human, machine and environment engineering was described in detail, including computer simulation of human, machine and engineering system, refrigeration system of ECS, life insurance system of flight vehicle, ground, air and space environment simulation technology and air conditioning. By summarizing advantages and limitations in these fields, suggestions and comments were given for further research efforts.
Comments on Multisensor Image Fusion Techniques
MAO Shi-yi, ZHAO Wei
2002, 28(5): 512-518.
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Multisensor image fusion is included in multisensor information fusion and has been applied widely. The techniques of image fusion are different from general information fusion techniques because of the particularity of images.The development condition about the multisensor image fusion is introduced firstly. Secondly, the main steps in image fusion process are described and the combinations of different sensors are given. The main image fusion methods, including multiresolution image fusion methods, methods based on wavelet and false color methods etc., are discussed. The performance of every method is analyzed qualitatively. The criteria how to evaluate image fusion method are given and the development directions of image fusion are pointed out finally.
Transgranular Shear Fraefure of High Strength Aluminum Alloys
CHEN Chang-qi
2002, 28(5): 519-523.
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In order to reveal the conditions for shear failure of high strength aluminum alloys, experimental tests and theoretical analysis were performed on various aluminum alloys and single crystals. It is concluded that plane strain deformation mode (external or internal) and very low strain hardening rate are two fundamental conditions for shear deformation localization to happen. Shear localization resulted in shear fracture. The author's previous proposed micro-mechanical model was revised.
Dynamic Response Analysis of Direction Control for SemiDifferential CoAxial Helicopter
CHEN Ming, HU Ji-zhong, CAO Yi-hua
2002, 28(5): 524-527.
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The dynamic equation of a semi-differential co-axial helicopter in vertical flight was set up and solved based on classical vortex theory and character of aerodynamic interference between upper and lower rotors of the co-axial helicopter. There exists a coupling relationship between vertical movement and direction rotation with direction control in vertical flight of the helicopter. Calculation example results indicate that the equations of dynamic response proposed for vertical movement and direction rotation reflect flight character of this helicopter.
Numerical Simulation for Steady Flow Field of CounterRotating Axial Fan
LI Qiu-shi, LU Ya-jun, LI Ling
2002, 28(5): 528-531.
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To enhance the stability and accurate when calculated the complicated turbomachinery rows, an inlet/outlet condition as called general boundary condition and an advanced strongly implicit iterative method named MSIP were presented. Based on rotational arbitrarily curved coordinate and RNG improved k-ε turbulence model, the three-dimensional calculating for a counter-rotating axial fan indicate that it is not appropriate to allocate the maximum load at the blade tip when make an aerodynamic design for axial fan or compressor, especially for counter-rotating system.
Studies on Scene Matching Algorithm of Fuzzy Similarity Metric
HUANG Xi-shan, CHEN Zhe
2002, 28(5): 532-535.
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Calculations of fuzzy image feature field were studied, the scene matching algorithm adopting similarity metrics of image fuzzy sets was proposed, and the matching methods of combining multiple similarity metrics of fuzzy sets were explored. Further more, the scene-matching algorithm of the fuzzy synthetic similarities (FSSM) was proposed. The simulation results show that the FSSM algorithm has advantages of excellent adaptability, high matching probability, and good real-time ability. As an excellent algorithm of scene matching, it can be used for the real-time positioning of aircrafts.
Target Recognition Method by Combination of Neural Networks with Evidence Theory
WANG Mao-lu, LI Shao-hong, MAO Shi-yi
2002, 28(5): 536-539.
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A method based on the combination of neural networks with D-S evidence theory was proposed to recognize HRR targets. Multiple HRR images were input into Learning Vector Qualification (LVQ) neural network to estimate target type evidence, the results were fused by D-S evidence theory. Methods for feature space discretization and class evidence estimation were proposed. The origin of recognition error of neural network was analyzed. The results of emulation show that the correctness of this method is higher than that of LVQ network method obviously, the ability to counteract disturbance and noise is also raised.
Morphology and Formation Mechanism of Primary TiB2 in TiAlB Alloys
ZHANG Hu, GAO Wen-li, ZHANG Er-lin, ZENG Song-yan
2002, 28(5): 540-542.
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Microstructure and phase constitution of Ti-53Al-xBalloys produced by an in-situ growing method were investigated by X-ray diffraction and scanning electron microscope respectively. The results show that these alloys are composed of TiAl and TiB2 phase, while the primary hexagonal prism TiB2 exhibits pyramidal protrusion or rod shape dendrites on its basal facets. The protrusions or rods exhibit facets which parallel to that of the primary TiB2. The solid-liquid interface stability of primary TiB2 was discussed and the formation mechanism of the morphology of primary TiB2 was investigated.
Effect of Apex Flap Length on Leading Edge Vortex Breakdown over Delta Wings
XU Yan, WANG Jin-jun
2002, 28(5): 543-546.
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The effectiveness of the apex flaps to control the vortex breakdown on a 70° sweep angle delta wings was studied experimentally. The angle of attack was in a range of 30°~50°. The flap angles and its length were found to be two important factors in determining the position of vortex breakdown in steady flow. Flow visualization results reveal that a drooping apex flap, effectively lowering the angle of attack of the portion of the wing closest to the apex can delay vortex breakdown. The variation in the flap angle produces a nonlinear effect on the vortex breakdown location, and it can be seen that the biggest flap produces the most significant effectiveness. The effect of the combination of the two apex flaps is better than that of single flap at α=35°.
Structure Characteristics of PhosphorusDoped Hydrogenated NanoCrystalline Silicon Films
YU Xiao-mei, WANG Jin-liang, JIANG Xing-liu, WANG Tian-min
2002, 28(5): 547-549.
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By Raman spectroscopy, high-resolution electron microscope and atomic force microscope, the structure of phosphorus-doped hydrogenated nano-crystalline silicon films (nc-Si (P)∶H) was analyzed The films possess orderly arranged cluster feature in the size of 15~20nm. The films are composed of nano-crystalline grain and amorphous silicon, the crystalline volume fraction of the films is 40％~55％, the average grain size is between 2 and 4 nm. The grain size, the crystalline volume fraction and the conductivity of the nc-Si (P)∶H increase as the doping concentration is increased. Compared with undoped hydrogenated nano-crystalline silicon films, the conductivity of nc-Si(P)∶H is increased almost 2 orders. Possible connection between the ordered cluster characteristics and the higher conductivity was finally appointed.
New Fault Detection Structure and Algorithm Based on Federated Filter
LIU Zhun, CHEN Zhe
2002, 28(5): 550-554.
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Based on federated Kalman filter, a new fault detection structure and algorithm was presented. The structure performs fault detection with the common states of local filters and reference filter. Chi-square test and Elman neural network test algorithm were presented. As an application, comparisons for these algorithms are simple and reliable, these algorithms can detect the errors for both sensors and reference system, and have excellent fault tolerance performances, fast fault identifying and isolating ability.
Research of Load Coaxiality Testing Technology
Lü Xiao-dong, LI Xin-jun, WANG Jing-tao
2002, 28(5): 555-558.
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An automated method for measuring load-coaxiality of universal testing machine was presented in two aspects: basic hypothesis, math modeling for calculating and processing. Based on the principle the modeling concept was proposed. From the models posed, a measuring system using computer-testing technology had been designed,which used three raster strain sensors as well as digital converters and it can measure the load-coaxiality and direction directly in real time. The method holds strong adaptation and applied foreground in engineering.
Measurements of Velocity Uniformity in Watertunnel Using DPIV
HUANG Zhan, SHEN Gong-xin, WEI Run-jie, GUO Hui
2002, 28(5): 559-562.
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A Digital Particle Image Velocimetry(DPIV)system using a special Pre-bias method was applied to flow field calibration measurements in the testing section of a water tunnel. Compared with the measurement results obtained by traditional methods (Pitot probe, LDV and traditional DPIV),the results show that the special Pre-bias method can improve measurement accuracy with almost one order level and is fit for flow field velocity uniformity measurement.
Numerical Prediction of Strength for 3D Braided Composites
LU Zi-xing, LIU Zhen-guo, MAI Han-chao, CHEN Zuo-ron
2002, 28(5): 563-565.
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Based on experimental investigation and finite element analysis (FEA) of braided composites, an empirical failure criterion of strength was proposed to meet the need of engineering application. A strength prediction method of 3D braided composites was introduced by using the model of modulus prediction and the results of FEA. Numerical calculation results indicate that the predicted strength of 3D braided composites agrees quite well with the results of tensile experiment.
Finite Element Analysis on Dynamic Properties of Spot Welding Robot
ZHOU Zheng-gan, LI Ran, YUN Chao
2002, 28(5): 566-569.
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To optimize structure design of spot welding robot, model analysis was performed on SIA-120 spot welding robot with ANSYS software by finite element method. Using the results of the model analysis, a proposed model was simulated and proven to be accurate by the simulation outcome. The imperfection of structure design of the robot was pointed out. With models in which improved design scenario was employed, parameters of dynamic properties of the ameliorative system were carried out quantificationally with ANSYS 5.5, which can provide a criterion for structural dynamic modification or design of similar robot.
Loading Spectra Development for Special Structural Members of Fighter
LIU Xiao-dong, LIU Wen-ting, WANG Zheng
2002, 28(5): 570-573.
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The approach and specialties of loading spectra development using maneuvers simulation technique for new-design aircraft were introduced in brief. Onthe above basis, the approach and key-points of developing stress/pressure spectrum for integral tank, gusts and sideslip spectrum for vertical tail were presented in detail. One key step of developing stress/pressure spectrum for integral tank is to calculate the pressure of the tank in all loading cases, and the G-A-G cycle should be taken into account for the analysis spectrum of the tank. The loading spectrum of the vertical tail is obtained by not only the simulation of maneuvers but also some statistical measurements.
Feed Network Design of Shaped Beam Slotted Array by Finite Element Method
WANG Jie, Lü Shan-wei
2002, 28(5): 574-577.
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Changing the angles of the centered-inclined slots was used to design the array feed's amplitude distribution. Changing the widths and lengths of the waveguides was used to design the array feed's phase distribution. A new design method of the feed network of shaped beam slotted array by finite element method was presented. In order to obtain the amplitudes and phases needed, the feed slot sizes, the feed excitation amplitudes and the phase network were calculated by finite element method. An example of design indicates the theoretical and experimental results are consistent well in the main shaped beam.
Investigation on Start Behavior of HydroViscous Transmission
ZHANG Yi-du, ZHANG Qi-xian
2002, 28(5): 578-580.
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Structure of the newly developed hydro-viscous soft start transmission is introduced and the hydroviscous-braking model is presented. The study on the hydro-viscous brake shows that a coupling relationship exists among the parameters of oil film thickness, hydro-viscous torque and friction disc speed. The variation of hydro-viscous torque is determined by the trend speeds to zero offriction disc speed and oil film thickness. When different patterns of oil film thickness are applied, hydro-viscous torque and friction disc speed will have obviously distinct characteristics.
Sneak Circuit Analysis Algorithm Research for Analog Switch Circuit
MA Qi-shuang, TANG Yao, ZHANG Ping-bo
2002, 28(5): 581-584.
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Compared several path search methodology of sneak circuit analysis, an algorithm of sneak circuit analysis for analog switch circuit was presented. The algorithm was applied successfully to the identification and searching of topology pattern of "H" pattern, Multi-Power pattern, Multi-Ground pattern sneak circuits. In order to verify the validity of the algorithm, a case analysis was conducted by using software based on this algorithm.
Experimental Study on Flow Construction over Spur Dikes
ZHANG Bai-shan, Lü Zhi-yong, ZHU Li-guo
2002, 28(5): 585-588.
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To understand effect of number and incidence of spur-dikes on flow pattern, flow construction over spur-dikes was studied by flow visualization and light sheet technique in a water channel. There are horse-shoe vortex around spur-dikes and Karman vortices behind spur-dikes. Depending on Reynolds number, flow patterns over spur-dikes can be divided into 4 types: steady single horse-shoe vortex; unsteady single horse-shoe vortex; unsteady double horse-shoe vortices Ⅰ and unsteady double horse-shoe vortices Ⅱ. If number and incidence of spur-dike decrease, intensity of horseshoe vortex and Karman vortices decrease.
Hierarchy Requirements and Verification for Cryptographic Protocols
LIU Yi-wen, LI Wei-qin
2002, 28(5): 589-592.
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The security requirements for cryptographic protocols were divided into shallow requirements and deep requirements. The hierarchy security requirements were illustrated. Using temporal logic and algebra, a formal requirement language was presented and used to describe the formal hierarchy requirements for cryptographic protocols. A model of computation was developed by modifying and extending the Abadi and Tuttle model, combining BAN logic and the NRL Protocol Analyzer. Using this model and theorem proving techniques, the formal requirements of the Otway-Rees protocol was verified.
Overbooking Risk of Civil Aviation Transportation
JU Yan-bing, FENG Yun-cheng, WANG Ai-hua
2002, 28(5): 593-596.
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Based on the experiences of managing risks of civil aviation companies, a Value at Risk (VaR) procedure was proposed to control overbooking risk．The calculation method of extra number of single-line and the representation of VaR of multi-line were given respectively． One whole company's VaR in a day was obtained from analyzing the relativity of return about different flights. Finally, an example on the risk analysis of one scheduled flight from Beijing to Hongkong was given to demonstrate the feasibility of VaR in the risk management of civil aviation transportation.
Integrated Evaluation Model of Reliability Based on Varied PopulationEnvironment Data
ZHAO Yu, HUANG Min
2002, 28(5): 597-600.
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Reliability data which come from the main testing phases of product developing course were supposed to be varied population\|environment data. Based on varied population-environment data, an integrated evaluation model of reliability was established. This model used Duane model of reliability growth as foundation, and introduced environment conversion factors under different testing conditions. An engineering method was recommended to solve the environment conversion factors. Based on the model, an integrated method and steps to evaluate product's reliability were determined. An example using practice data was presented.
Numerical Simulation of 3D Aerospike Nozzles
DAI Wu-ye, LIU Yu, MA Bin
2002, 28(5): 601-604.
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Based on three-dimensional Reynolds averaged Navier-Stokes equations and low Reynolds number k-ε equations, a numerical program to simulate the 3D flowfield of aerospike nozzle was developed by employing two-order Non-oscillatory and Non-free-parameters Dissipative finite difference scheme. The 3D flowfield of a linear aerospike nozzle and a tile-shaped aerospike nozzle at different flight altitude were predicted. The results indicate that the pressure distribution on the plug of a tile-shaped aerospike nozzle have the advantage of load uniformity, and the cylindrical plug can load more than the planar plug under the same conditions.

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